1、概述
案例:基于稠密光流的视频跟踪
API介绍:
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calcOpticalFlowFarneback( InputArray prev, InputArray next, InputOutputArray flow, double pyr_scale, int levels, int winsize, int iterations, int poly_n, double poly_sigma, int flags ); |
- prev:前一帧单通道CV_8UC1图像
- next:当前帧单通道CV_8UC1图像
- flow:输出的光流数据
- pyr_scale:金字塔上下两层的尺度关系
- levels:金字塔层数
- winsize:窗口大小
- iterations:迭代次数
- poly_n:像素领域大小,一般是5、7
- poly_sigma:高斯标准差一般是1~1.5
- flags:计算方法:主要包括OPTFLOW_USE_INITIAL_FLOW和OPTFLOW_FARNEBACK_GAUSSIAN
实现步骤:
1.实例化VideoCapture
2.使用其open方法打开视频文件
3.获取视频第一帧并得到其灰度图(因为稠密光流输入只支持单通道8位)
4.while(true)循环读取视频帧
5.将当前帧灰度化
6.执行稠密光流函数,并输出光流数据
7.将光流数据绘制出来
8.显示光流数据
2、代码示例
(ps:界面中的按钮元素使用到了Qt)
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HF_Object_Tracking::HF_Object_Tracking(QWidget *parent) : MyGraphicsView{parent} { this ->setWindowTitle( "稠密光流对象跟踪" ); QPushButton *btn = new QPushButton( this ); btn->setText( "选择视频" ); connect(btn,&QPushButton::clicked,[=](){ choiceVideo(); }); } void HF_Object_Tracking::choiceVideo(){ path = QFileDialog::getOpenFileName( this , "请选择视频" , "/Users/yangwei/Downloads/" ,tr( "Image Files(*.mp4 *.avi)" )); qDebug()<< "视频路径:" <<path; hfObjectTracking(path.toStdString().c_str()); } void HF_Object_Tracking::hfObjectTracking( const char * filePath){ VideoCapture capture; capture.open(filePath); if (!capture.isOpened()){ qDebug()<< "视频路径为空" ; return ; } Mat frame,gray; Mat prev_frame ,prev_gray; Mat flowResult,flowData; capture.read(frame); //读取第一帧数据 //转灰度图 cvtColor(frame,prev_gray,COLOR_BGR2GRAY); //将frame转灰度图赋值给前一帧 while (capture.read(frame)){ cvtColor(frame,gray,COLOR_BGR2GRAY); if (!prev_gray.empty()){ //稠密光流跟踪 calcOpticalFlowFarneback(prev_gray,gray,flowData, 0.5, 3, 15, 3, 5, 1.2, 0); cvtColor(prev_gray, flowResult, COLOR_GRAY2BGR); for ( int row = 0; row < flowResult.rows; row++) { for ( int col = 0; col < flowResult.cols; col++) { const Point2f fxy = flowData.at<Point2f>(row, col); if (fxy.x > 1 || fxy.y > 1) { line(flowResult, Point(col, row), Point(cvRound(col + fxy.x), cvRound(row + fxy.y)), Scalar(0, 255, 0), 2, 8, 0); circle(flowResult, Point(col, row), 2, Scalar(0, 0, 255), -1); } } } imshow( "flow" , flowResult); imshow( "input" , frame); } // imshow("frame",frame); int key = waitKey(1); if (key==27){ break ; } } } |
3、图像演示
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原文链接:https://blog.csdn.net/m0_60259116/article/details/129101263